"The numbers are fantastic," said Dr Fred Locke, a blood cancer expert at Moffitt Cancer Center in Tampa who co-led the study.

"These are heavily treated patients who have no other options."

The treatment, which has been dubbed 'a living drug' by doctors, works by filtering a patient's blood to remove key immune system cells called T-cells, which are then genetically engineered in the lab to recognise cancer cells.

Cancer cells are very good a evading the immune system, but the new therapy essentially cuts the brakes, allowing immune cells to do their job properly.

Martin Ledwick, Cancer Research UK’s head cancer information nurse, said: “These results are promising and suggest that one day CAR-T cells could become a treatment option for some patients with certain types of lymphoma.

"But, we need to know more about the side effects of the treatment and long term benefits.”

Experts prepare blood cells from a patient to be engineered in the lab to fight cancerCredit:
Kite Pharma

Patients in the study had one of three types of non-Hodgkin lymphoma, a blood cancer which affects 13,600 patients in Britain, and had failed all other treatments. Most patients with such an advanced condition only live for six months but half of the trial group are still alive nine months since the trial began, and a third may be cured.

Dimas Padilla, 43, of Orlando, who was warned his case was worsening after chemotherapy stopped working, is now in complete remission after undergoing the therapy last August.

After learning his cancer was probably terminal he said: "I was thinking how am I going to tell this to my mother, my wife, my children," he said.

After CAR-T therapy he saw his tumours "shrink like ice cubes" and is now in complete remission.

However there are still concerns that the treatment has significant side effects, and can even kill some patients, as it puts the immune system into a state of over-drive. During the trial two people died from the therapy, rather than their cancer.

Of the study participants, 13 per cent developed a dangerous condition where the immune system overreacts in fighting the cancer, and roughly a third of patients developed anaemia or other blood-count-related problems.

Nearly one third also reported neurological problems such as sleepiness, confusion, tremor or difficulty speaking, but these typically lasted just a few days.

The scans show how cancer has disappeared after just three months, and the remission has continued